Well casing contact tool



B- BLANK, JR

WELL CASING CONTACT TOOL 3 Sheets-Sheet 1 Filed Aug. 28, 1968 ,N J R E K O V N W 5 m m A 3 B a v y D L E W 2 W W B 7 u 2 3 3545362 run 020- fiat! IDIZD Dec. 15,1970 w. a. BLANK, JR 3,548,362

WELL CASING CONTACT TOOL Filed Aug. 28, 1968 5 Sheets-Sheet z INVENTOR WINFIELD 'B. BLANK, JR.

ATTORNEYS Dec. 15, 1970 w. B. BLANK, JR

WELL CASING CONTACT TOOL Filed. Aug. 28; 1968 3 Sheets-Sheet 5 INVENTOR WINFIELD B. BLANK, JR.

.nited States Patent Offlce 3,548,362 Patented Dec. 15, 1970 3,548,362 WELL CASING CONTACT TOOL Winfield B. Blank, Jr., Tulsa, Okla., assignor to Sinclair Oil Corporation, a corporation of New York Filed Aug. 28, 1968, Ser. No. 756,043 Int. Cl. H01r 11/20 US. Cl. 33995 6 Claims ABSTRACT OF THE DISCLOSURE An apparatus for establishing electrical contact with the casing within a well bore which can be either raised or lowered within the bore Without removal of the apparatus from the bore. The apparatus is lowered to the desired depth within the well bore, and then a slight lifting motion causes relative movement between first and second body members of the apparatus. As a result, a stepping'cam causes a rotating latch to move over a lobe on a locking cam. This releases a camming wedge'which pivots blades to their extended position in which they contact the well bore. When it is desired to change the location of the apparatus, another slight lifting motion causes the latch to step to the next lobe of the locking cam, returning the camming wedge to its initial position in which it pivots the blades to their retracted position.

The present invention pertains to a downhole tool for use within a well casing or other pipe. More particularly, the present invention pertains to such a tool used to establish electrical contact within the pipe.

In many operations, for example corrosion determination, it is desired to establish electrical contact at a point within a well casing. In corrosion determination, for example, electrical contact is established with the well casing at two or more locations at different depths within the well separated by a known distance. The difference in electrical potential between the two locations provides information useful in corrosion determination.

While well bore tools including motor driven blades which contact the well casing to establish electric'alfjcontinuity are known, such apparatus are cumbersome to use. in addition to being expensive. Other well bore-'ftools include blades which are held in a retracted positionuntil the apparatus is lowered to the bottom of the well bore. at which time the blades are released to contact the. well casing. Electrical readings are made as the apparatus is raised in the well bore. With the blades in their extended position, the apparatus cannot be lowered within the well bore. Consequently, if a location at which a reading is desired is inadvertently passed, the apparatus. must be lifted from the well, the blades returned to their retracted position, and again the apparatus lowered into the well to the desired depth. This is an extremely time consuming operation. Due to the great depths at which readings are desired within a well bore, removal of the apparatus from the well and return of the apparatus to the desired depth might require several hours.

The present invention is an apparatus for establishing electrical contact with a well casing at any desired depth within a well bore in which, even after electrical contact is initially made, the location. of the apparatus can be either raised or lowered without removingthe apparatus from the well bore. The apparatus is lowered into a well bore to a desired depth, and then the apparatus is lifted slightly, releasing blades from a retracted position in which they are kept out of contact with the well casing to an extended position in which they contact the well casing. The blades penetrate any thin layers of oil, corrosion, etc. which might be on the inner surface of the well casing, thus establishing electrical contact with the casing.

The apparatus includes first and second body members slidingly connected to each other and held together by a spring biased camming wedge. The apparatus is lowered to the desired position within the well, and then a slight lifting on the cable from which the apparatus is suspended raises the upper body member, while the lower body member remains substantially stationary. A stepping cam and rotating latch move with the upper body member. The stepping cam causes the latch to rotate and step over a lobe on a locking cam that remains. substantially stationary with the lower bodymember. In its new position, the rotating latch allows the upper body member to slide within the lower body member. As a consequence, the camming wedge is forced down to cause a plurality of knife blades to pivot from their retracted position within the lower body member to. their extended position in which they contact the well casing, penetrating any oil or corrosion layers on the surface of the casing.

When it is desired to move the apparatus to another location within the well casing, the apparatus is again given a slight lift. The stepping cam then causes the latch to rotate, whereby it remains in its raised or locked position in which the camming wedge causes the knife blades to pivot back to their retracted position within the lower body member. As a consequence, the apparatus can then be moved either up or down within the well casing. Thus, the knife blades can be changed from their retracted position to their open position or vice versa simply by giving the apparatus a slight lift. With this apparatus it is thus possible to obtain readings at locations within the well casing in random order rather than having to start at the bottom of the casing and only move the apparatus upward. Consequently, if the location at which a reading is desired is'bypassed, the apparatus can be conveniently lowered to that location without removing the apparatus from the well bore.

These and other aspects and advantages of the present invention are apparent in the following detailed description and claims, particularly when read in conjunction with the accompanying drawings in which like parts bear like reference numerals. In the drawings:

FIG. 1 is a sectional view of the apparatus of the present invention;

FIG. 2 is an elevationalview of the apparatus;

FIG. 3 is a plan view {of a locking cam suitable for use in the apparatus of the present invention;

FIG. 4 is a view taken along line 44 of FIG. 3;

FIG. 5 is a diagrammatic representation of the outside development of the locking cam of FIG. 3;

FIG. 6 is a horizontal view of a stepping cam suitable for use in the apparatus of the present invention;

FIG. 7 is a plan view of the stepping cam of FIG. 6;

FIG. 8 is a view taken along line 88 of FIG. 7;

FIG. 9 is a horizontal view of a latching member suitable for use in the apparatus of the present invention;

FIG. 10 is a plan view of the latching member of FIG. 9; and

FIG. 11 is a view taken along line 11--11 of FIG. 10.

In FIGS. 1 and 2 downhole well tool 10 includes first body member 12 and second body member 14. Member 12 is made up of a top assembly 16 and a central assembly 18, held together, for example by nut 20 threaded onto one end of central cylindrical portion 19 of central assembly 18. Top assembly 16 and central assembly 18 are electrically insulated from each other, for example by means of insulating washers 22 and 24.

Lower body member 14 includes lower assembly 26 and body element 28, which are held together, for example by nut 32 threaded onto body element 28. In addition lower body member 14 includes housing element 30 which is connected to body element 28 by suitable means such as @t screws (not shown). Lower. assembly 26 is electrically insulated from the remainder of the apparatus, for example by means of insulating washers 34 and 35.

Body element 28 includes an elongated cylindrical portion 36 extending within a central opening in housing element 30 and surrounding the elongated cylindrical portion 19 of central assembly 18. Locking cam 40 rests upon ridge 38 of body element 28 and is attached to housing element 30 and body element 28 by means such as set screws. Centrally located within locking cam 40 and supported, for example by nut 42 threadedly connected on the second end of cylindrical portion 19 of central assembly 18, is stepping cam 44. Within stepping cam 44 is located rotating latch member 46 which includes radial flanges 48, 48', 49 and 49', that rest upon the upper edge of stepping cam 44.

Coil spring 50 encircles the central section of cylindrical portion 19 of central assembly 18. The lower end of spring 50 rests against the upper edge of the rotating llatch member 46. The upper end of spring 50 backs against camming wedge '52 which also encircles the elongated cylindrical portion 19 of central assembly 18.

Housing element 30 encloses elongated cylindrical portion 36 of body element 28 and also all of the components 40-52. Spaced about housing element 30 are elongated openings 54 in each of which a knife 56 is pivotally mounted. Each knife 56 includes an elongated'blade 57, a pivot '58 and a control portion 59.

A first insulated electrical wire 60 passes through top assembly 16 and is electrically connected to central assembly 18, for example by means of screw 62. A second insulated electrical wire 64 passes through top assembly 16 and through a central bore 65 in the elongated cylindrical section 19 of central assembly 18 from which it passes through body element 28 and emerges from lower assembly 26. This second wire 64 is electrically connected to another assembly 10 located lower down within the well bore.

As depicted in detail in FIGS. 3, 4 and 5, locking cam 40 has an outer cylindrical surface and has its lower edge normal to the axis of the cylinder. Cam 40 includes two sets of cam elements, each set having three camming lobes. FIG. depicts the outside development of locking cam 40. The first camming lobe 102 extends downward from peak 104 to corner 105 at an angle of approximately 30 for a distance of approximately 45 around the circumference of locking cam 40. From there camming lobe 106 rises vertically to approximately the same height as camming lobe 102. Lobe 106 then extends downward at an angle of approximately 30 for a distance of approximately 22.5 around the circumference of locking cam 40.

The outside development of locking cam 40 then drops vertically to groove 108 which extends horizontally for a distance of approximately 33.75 around the circumference of locking cam 40. Camming lobe 110 then extends horizontally for a distance of approximately 45 around the circumference of locking cam 40 at approximately the same height as corner 105. The outside development then includes a second groove 112, extending horizontally approximately 33.75 around the circumference of locking cam 40 at approximately the same height as groove 108. This brings the outside development of locking cam 40 to a point 180 around its circumference at which a second identical set of camming lobes 102-112' commences.

The outside diameter of locking cam 40 is just less than the inside diameter of cylindrical portion 36 of body element 28. Portions 108, 110, 112, 108', 110' and 112' of locking cam 40 have a uniform inside diameter D1."

Camming lobes 102 and 102' each include a first portion 116 having an inside diameter D2, slightly less than D1, and a second portion 118 having an inside diameter D1. Cammings lobes 106 and 106' each have an inside diameter D2.-

FIGS. 6, 7 and 8 depict stepping cam 44 which has a hollow cylindrical body with an outer cylindrical surface 119 and a lower surface 120 substantially perpendicular to the axis of the cylinder. Cylindrical surface 119 has an outside diameter slightly less than the inside diameter D2 of camming lobes 106 and 106 and of portions 116 and 116' on locking cam 40. Interiorly, stepping cam 44 includes a first section 122 having a substantially large internal diameter, and a second section 124 having a smaller internal diameter. The upper surface of stepping cam 44 comprises a plurality of stepping lobes 126, for example, eight stepping lobes. Each stepping lobe 126 commences from a low point 128 and rises to a peak 130, then descends to a second low point 128 from which the next adjacent stepping lobe 126 rises. Each peak 130 includes a cog 132, formed over substantially half of its stepping lobe 126 and centered about the peak 130. Each cog 132 comprises a portion of stepping cam 44 having an increased outside diameter and extending a short distance down the length of stepping cam 44. The outside diameter of stepping cam 44 at these cogs 132 is slightly less than the larger inside diameter D1 of locking cam 40.

Rotating latch 46 is depicted in FIGS. 9, l0 and 11 and includes a hollow cylindrical body portion 134 having four radially extending lobes 48, 48', 49, and 49' substantially equally spaced about the circumference of latch 46 and extending over substantially the upper one-half of its height. The lower surface 136 of each lobe 48, 48', 49 and 49 is tapered at an angle of approximately 30". Each lobe has a width of approximately 22.5 around the circumference of latch 46. Interiorly, latch 46 has a diameter slightly greater than the outside diameter of cylindrical portion 19 of central assembly 18. The outside diameter of cylindrical portion 134 is slightly less than the inside diameter of upper section 122 of stepping cam 44. The outside diameter of latch 46 across its lobes 48-48 and 49-49 is slightly less than the outside diameter of locking cam 40.

Stepping cam 44 and rotating latch 46 are assembled upon cylindrical portion 19 of central assembly 18 as depicted in FIG. 1, with coil spring 50 compressed between latch 46 and camming wedge 52. Cylindrical portion 36 of body element 28 surrounds these components. One of the lobes 126 of stepping cam 44 is located at portion 118 of locking cam 40. Likewise, another lobe 126 is located at portion 118' on the opposite side of locking cam 40. The one lobe 126 is locked between the portion 116 and lobe 106 which have a smaller inside diameter D2. Similarly the other lobe 126 is locked between portion 116' and lobe 106'. Consequently, stepping cam 44 is prevented from rotating within locking cam 40, but is permitted to ride up and down with locking cam 40.

When assembly 10 is lowered into a bore hole, the weight of 'lower assembly 14 and everything connected below it is transmitted through portion 59 of knives 57 to camming wedge 52 which is resting on sleeve 183 which in turn rests on rotating latch 46. Sleeve 183 limits the upward movement of assembly 18 through camming wedge 52. Consequently, camming grooves 138 in camming wedge 52 act against control portion 59 of each knife 56 to keep the knives 56 in their closed position with blades 57 retracted within housing element 30. Assembly 10 is then lowered to the desired depth within the well bore. A slight upward motion is then exerted on the cable from which assembly 10 is suspended. The drag caused by the weight and inertia of lower assembly 26 and body element 28 causes a relative sliding motion between top assembly 16 and central assembly 18, which are rigidly connected together, and housing element 30, body element 28 and lower assembly 26, which are likewise rigidly connected together. Since stepping cam 44 and rotating latch 46 are supported on central assembly however, remains with body element 28. Thus relative motion takes place between locking cam 40, on the; one hand, and stcpping cam 44 and rotating latch 46, on the other hand. As a consequence,' v the lobe 48 of latch 46 is raised from camming lobe 102 to camming lobe 106. When lobe 48 clears the top of camming lobe 106, spring 50 acts on latch 46. As a consequence, peak 130 of cog 132 moves upon sloped surface 136 of lobe 48, causing latch 46 to rotate within cams 40 and 44 so that lobe 48 is upon camming lobe 106. Latch l46 continues to rotate as lobe 48 slides down lobe 106, falling into groove 108. Latch 46 has thus roiated approiiimately 45 relative to locking cam 40 and stepping cam 44. Since groove 108 is substantially below corner 105, latch 46 is at a lower position withiii assembly 10. Consequently, the central assembly 18' and its associated parts are allowed to move downward, and

so cylindrical portion 137 of central assembly 18 bears on the top of camming wedge 52, pushing the camming wedge down. Camming grooves 138 of wedge 5,2'then act upon the control portions 59 of knives 56 to'cause the khives 56 to pivot about pivots 48 to their extended position. Then as assembly 10 is lowered within the well bore, blades157 of knives 56 penetrate the inner surface of the well bore, establishing electrical contact with the well bore. 1

When it is desired to move assembly 10 to a dilierent location within the well bore, assembly 10 is first given a slight lifting motion. This lifting motion again causes stepping cam 44 to raise rotating latch 46. When this happens the next lobe 49 of latch 46 is raised rrsm its position on groove 112' to camming lobe 102 on kicking cam- 40. As a consequence, latch 46 rotates as lobe 49 falls down to corner 105. Latch 46 is then retained in its upper position with lobes 48, 48', 49, and 49,r le sting respectively'against lobes 110 and 110 and corners 105 and 105'. This raises spring 50 and camming wedge 52, thereby closing blades 56. Assembly can then be moi-red to its next position, either lower or higher within the well bore. When that next position is reached, aslight lifting motion upon'assembly 10 causes rotating'f'latch 46 to rotate another 45 so that lobes 48, 48', 49, aii'd 49' are' resting respectively on grooves 112 and 112] and grooves 108 and 108. This lowers cammingwedge 52 to return blades 57 to their extended positions. Thus each lifting motion on assembly 10 causes rotating latch 46 to rotate 45 within locking cam 40 and stepping cam 44., Each 45 rotation causes the position of knives"56 to change from open to closed or from closed to open? Consequently, it is possible to move assembly 10 either up or down within the well bore without having to removethe assembly 10 from the well bore to return knives 56 to their closed position. v

Cylindrical sleeve 183 can be positioned within the turns of coil spring 50 to limit the travel of assembly 18 through wedge 52 to any degree desired. The relative movement between upper body member 12 and lower body member 14 is limited by camming wedge 52 and sleeve 183. Thus as lower body member 14 slides downward relative to upper body member 12, camming wedge 52 can move down toward cam 44 and latch 46, which are prevented by nut 42 from moving downward. The distance wedge 52 can move is limited by cam 44 and latch 46, and by spring 52 and sleeve 183.

Although the above description has been with reference to a preferred embodiment, numerous modifications and changes could be made and still the resulting apparatus would be within the scope of the invention.

What is claimed is:

1. Apparatus comprisinga first body member; a second body member connected to said first body member for limited motion relativgthereto; at least one blade member movably connectedto one of said body members; camming means capable of assuming a first camming position in which said caming means acts on said blade member to move said blade member to a first blade position within said one of said body members and capable of assuming a second carrifming position in which said camming means acts on said blade member to move said blade member to a second blade position extended from said one of said body members, said camming means limiting the relative motion between said body members; and stepping means including abfirst cam member, a second cam member, and a latching member; said first and second cam member movable with said first and second body members respectively; said' latching member responsive to relative] motion between said first and second cam members for movement befween a first latching position in which said latchingmeans causes said camming means to assume} said first camming position and a second latching position in which saidlatching means causes said camming means to assume said second camming position.

2. Apparatus as claimed in claim 1 in which said blade member is pivotable between said first blade position and said's'econd blade position.

3'. Apparatus as claimed in claim 1 in which relative motion between said first and second cam members causes saidJatching member to rotate relative to said cam members.

4; Apparatus as claimed in claim 3 in which said blade member is pivota-ble between said first blade position and said second blade position.

5. Apparatus as claimedin claim 1 further comprising first circuit means electrically connected to one of said body members.

6. App items as claimed in claim 5 in which said first and second body members include a central bore for passage of second circuit means therethrough.

Refereirces Cited UNITED STATES PATENTS 1,091,502 3/1914 Gearing l279 3,324,389 6/1967 Blank, II 32462 MARVIN A. CHAMPION, Primary Examiner I. H. .McGLYNN, Assistant Examiner A US. Cl. l75- -286; 324-1 

